Many and various type advances have been made in the wheel and brake arts and these include advances in the configurations and compositions of the wheels, the tires, and the brake disks of a wheel and brake assembly. These efforts have been particularly concentrated in the aircraft industry as advances in aircraft performance have been achieved. While modern aircraft fly faster, they also take off and land at faster speeds than their earlier counterparts and in this circumstance it has become necessary to also advance the state of the art as it pertains to wheels and brakes to insure aircraft safety.
A particular advancement in the brake art has been the development of the carbon composite brake disk which proved to provide a high degree of braking while contributing a marked reduction in the weight of an aircraft brake assembly. A particular problem remains in that very high temperatures are generated during aircraft braking and especially in an emergency braking of an aircraft. These high temperatures affect many elements of the wheel and brake assembly including structurally critical components as well as the tires and various electronic sensors which may be present to gain information of wheel and brake performance. The detrimental affect of high temperature has been so great that, when an aircraft experiences an aborted take-off due to an emergency on the aircraft, the industry considers that all of the components of the wheel and brake assembly except the axle must be scrapped for the sake of safety considerations.
To accomodate high heat sink temperatures, shielding and insulating features have been incorporated into wheel and brake designs. These features protect critical components from overheating in normal service and from heat related failure in an emergency braking situation. However, the desire of aircraft manufacturers is to continually reduce weight both structurally and in the heat sink to provide for maximum aircraft performance and payload. The present invention provides a means to reduce heat sink weight for a fixed brake energy capacity or, provides significantly increased energy absorption capacity for a fixed heat sink weight.
It is, therefore, in accordance with a primary aspect of the present invention an object to provide a configuration for a brake disk for aircraft multi-disk brake assemblies which increases brake energy capacity during braking of a high speed rotating aircraft wheel.
According to another aspect of the invention, it is an object to provide a rotor and/or stator disk of a multi-disk brake assembly which incorporates a volume of a phase change material within the disk body structure between its brake wear face surfaces such as to absorb large quantities of heat as the material changes states without being accompanied by an increase in temperature during braking action.
In accordance with another aspect of the invention it is an object to provide a brake disk having at least one cavity particularly configured within the body of the disk between its outer planar brake wear faces, which cavity is adapted to carry a volume of a phase change material therein go as to increase energy absorption capacity during braking of an aircraft wheel.
According to still another aspect of the invention it is an object to provide a brake-disk having a configuration of cavities within the body of friction material comprising the disk wherein the geometric arrangement of cavities is such as to define a structural truss configuration which maintains the structural strength characteristics of the disk, said cavities adapted to carry a specific volume of a phase change material therein for increased energy absorption capacity of the disk.
In accordance with still another aspect of the invention it is an object to provide a brake disk comprised of fully densified carbon composite material having a central annular core comprised of a vapor deposited phase change material in a low density, high strength, carbon matrix, said brake disk exhibiting high energy absorption qualities when subjected to braking action within a multi-disk brake stack of an aircraft wheel and brake assembly.